1. Field of the Invention
The present invention relates to an apparatus achieving a high density, zero-height board-to-board interconnect, and, more particularly to an apparatus suited for optical and electrical interconnections.
2. Description of the Related Art
Modern electronic equipment widely employ electrical connectors. Often, electrical connectors are utilized for coupling printed circuit boards together. One typical use of a connector is for connecting main circuit boards, or mother boards to other circuit boards, or “daughter boards.”
Typically, mother board connectors include a “card edge” including housing with rows of conductive contacts within a slot for receiving a daughter board with contact pads. Mother board connectors typically include spring biased conductive contacts for maintaining electrical contact with the daughter board. Other types of contacts for mating mother boards to daughter boards include fork and blade contacts, and pin and receptacle contacts. Also known are flexible circuits for connecting points on a printed circuit board. Flexible circuits include conductive traces disposed on a flexible substrate with pressure mounted connectors for making contact between printed circuit boards.
When making connections between printed circuit boards, the considerations for determining the type of connector include the interconnection height, required signal density and the amount of mechanical float. Typically, connections between printed circuit boards occur in only a single axis due to the mating connectors' requirement to be displaced during interconnection. When additional axes of connection are required, connectors must be made to float, flex or rotate. For example, a printed circuit board with two axes requiring connections typically must have one or both connectors with the ability to float, flex or rotate into position. The mechanical difficulties in the typical two axis connector results in a limited number of signals. Attempts at employing flexible circuits have proved disadvantageous due to the decreased signal density and decreased reliability of flexible circuits. Further, flexible circuits typically bend in only one dimension.
The problems of connecting in multiple dimensions is compounded for circuit board interconnections of optics modules to mother boards. More particularly, optics modules require both electrical and optical interconnections to be mated, but with different displacements and different axes. Typically, optical connectors require large displacements during the mating of the connectors and in a different axis than the electrical connectors. As a result, the prior art teaches a board-to-board electrical connector with a discrete connection height for the electrical connection in tandem with optical connectors on loose fiber “pigtails” for optical connections. However the “pigtails” for optical connections present problems of signal density and reliability. In typical board-to-board interconnections, the electrical connectors present problems with distance between the circuit boards in space-limited applications.
What is needed is a connection mechanism that allows electrical and optical connections to be made on a single module with zero height between the module and the mother board. Additionally, what is needed is a connection mechanism that allows multiple axis connections.